Fred Miranda wrote:
I just got the Astrotrac mount yesterday and took a couple test shots from my light polluted backyard.
As a hobby, I read about astronomy and can identify some constellations but have no astrophotography experience. To make things worse, there was a very bright full moon out there...but I had to test my new toy!

First, I mounted the Astrotrac on my RRS ball-head as Steve suggested. From my tests, aligning is possible but challenging...actually quite frustrating.
However, when mounted on the Astrotrac TW3100 Wedge instead, aligning Polaris took only about 20 seconds. The fine adjustments on this head are easy and super precise.
This gave me the confidence I needed to push the limits and attach my Canon 500mm f/4L IS II on it. I was surprised how rock solid the entire thing was with this heavy lens but was not expecting good tracking with such big focal length.
So, I aimed it to the Orion Nebula and focused on it using 10x live view. I recommend re-visiting Polaris alignment with a heavy lens is added. I took a 45s exposure and the result is below. I removed light pollution in Lightroom. It's nothing great but I'm happy with my first astro shot!...Show more →
Awesome shot Fred.
Harsha

astro-ep wrote:
Definitely an ambitious start with great first result, Fred. Congratulations !

That's a lot of lens for an Astro-Trac! With 500mm and a full frame sensor, you're shooting at a resolution similar to my set-up (~3.5 arc-sec per pixel). If you have the new Astro-Trac, you might want you give autoguiding a try (when you shoot with that 500mm howitzer).

From my perspective, the main problem with Astrophotography is that it is very addictive. I started shooting with a Canon 30D and a 200mm L lens on a Losmandy GM8 equatorial mount, and my first shots were not as good as yours. I wanted deeper shots and rounder stars. 4 years later, I'm shooting with dedicated deep sky Astrophotography gear (when the weather permits).

Fred Miranda wrote:
Thanks guys. I can see how this can become quickly addictive.
For those who only want even more portability shooting Nightscapes with their wide-angle or lighter lenses, there is now a great alternative to Astrotrac.
It's called iOptron SkyTracker and its design is very similar to the great Vixen Polarie but with many improvements like an included illuminated scope, ability to hold 6.6 pounds of weight, a built-in wedge and 24hr battery performance. Since my main interest is landscape photography, I just ordered one to try it out.
B&H has is for $399:

I'm also working on a quick tutorial on how to blend two images together when shooting low ISO Nightscapes with a tracking mount: One long exposure for the tracked stars and the other for the foreground elements....Show more →

Wow Fred.....you're a quick study, and not shy about throwing on a 500mm to peak the challenge. Great results with the Astro, and I'm very interested in your impressions on the iOptron - it would be my choice for size/weight reasons, and it looks like you wouldn't need the geared head with it? Looking forward to your blending tutorial...thank you!

astro-ep wrote:
Definitely an ambitious start with great first result, Fred. Congratulations !

That's a lot of lens for an Astro-Trac! With 500mm and a full frame sensor, you're shooting at a resolution similar to my set-up (~3.5 arc-sec per pixel). If you have the new Astro-Trac, you might want you give autoguiding a try (when you shoot with that 500mm howitzer).

From my perspective, the main problem with Astrophotography is that it is very addictive. I started shooting with a Canon 30D and a 200mm L lens on a Losmandy GM8 equatorial mount, and my first shots were not as good as yours. I wanted deeper shots and rounder stars. 4 years later, I'm shooting with dedicated deep sky Astrophotography gear (when the weather permits).

Eric,
You've captured incredible images. Thanks for sharing them. I can see you got to the point of no return!

Trying my 500 II on it was not my initial intention and I was shocked to get something to work with on a full moon sky. I almost attached my 1.4x extender on it.
When focusing using Live View at 10x, I could see the stars moving rather fast. The Astrotrac wedge gave me the confidence for its precise and stable alignment.

Tracking errors and noise are both best dealt with in shorter exposures. Think this is the chief reason you see stacked images.

Also... margin for error is much slimmer with one frame.

(been into visual astronomy for a while and used to read about astro-imaging quite a bit)

Stacking makes for a more malleable final image in post. Believe the reason for this is that the bits of noise from the sensor are randomly distributed and when combining images you're exchanging noise for "good" pixels. The idea being the more you stack the less noise you'll have as noisy pixels are increasingly exchanged for good. (less noise also allows you to push shadows/exposure/etc in post as well)

As an alternative to tracking...

There are actually techniques for stacking foreground and sky separately. We usually see this done for the foreground when you see something like star-trails. However, there is software that will allow you to stack stars. (effectively blurring foreground)

In theory you could snap off a bunch of shots for the same scene... stack one for foreground, one for stars, and combine them in post. Been meaning to try this eventually. Not sure how difficult it would be. In theory, though, should be able to achieve results similar to a tracking device without actually having one.

Fred Miranda wrote:
Todd,
Love that you included the horsehead and flame with the orion nebula. Thanks for sharing!
Did you mod your camera?
Fred

Hello Fred,

Thanks. I used the Nikon D3 for that image, I have the D800 & D800E now (much better cameras).
The D3 was not moded, I used Nikon Capture NX2 to process the image. The color control points do a great job with the colors... I hope you get more practice with your astroTrac soon. I'd like to see more images.

moonpeep wrote:
Stacking makes for a more malleable final image in post. Believe the reason for this is that the bits of noise from the sensor are randomly distributed and when combining images you're exchanging noise for "good" pixels. The idea being the more you stack the less noise you'll have as noisy pixels are increasingly exchanged for good. (less noise also allows you to push shadows/exposure/etc in post as well)

actually, that's slightly off. Believe the benefit is from averaging noise for a pixel, not replacing a pixel with another. (at least I don't know of an algorithm for this)

Fred Miranda wrote:
Eric,
You've captured incredible images. Thanks for sharing them. I can see you got to the point of no return!

Trying my 500 II on it was not my initial intention and I was shocked to get something to work with on a full moon sky. I almost attached my 1.4x extender on it.
When focusing using Live View at 10x, I could see the stars moving rather fast. The Astrotrac wedge gave me the confidence for its precise and stable alignment.

I have the new AG version and realized that a precise alignment is crucial for declination with long FLs because as far as I know, with the Astrotrac, an autoguider only works in right ascension axis.

From the info I've read, it's almost better to take many stacked photos using the same exposure. Staking is well-known for increasing S/N ratio but can we get extended dynamic range?
Fred...Show more →

Thanks for taking a look Fred... and you're right about being at the point of no return.

I personally have not used the LVI smartguider. I use a separate CMOS sensor through a device called an off-axis guider. You can see the set-up here:

The guide camera is the small square box, on top of the scope, near the rear. For my astro set-up, it simply connects to the software on my laptop (MaximDL), and it handles all the guiding. For portability, I'd think you would want a self contained guider, like the LVI, or similar. But you'll generally get better results with a laptop and separate guide camera. You can use a free copy of PHD :

Regarding stacking, it's definitely better to stack, than a single frame (at least in most amateur applications). Stacking helps fill-in the noise, found in a single sub-frame (increases the S/N). 10 is better than 1; 100 is better than 10... I stack all my images. I also calibrate, with flats, bias and dark frame subtraction. You'll find that a stacked & calibrated image will be much easier to process. Also, you want to shoot in RAW, to stack the highest bit-depth that the camera allows. You'll be able to stretch and push the processing much better in 12, 14 or 16 bit.

Here's a quick write-up on calibration:http://deepskystacker.free.fr/english/faq.htm
Also, Deep Sky Stacker is a free image stacking package, if you wanted to give it a try. You can stack in Photoshop, but if you're stacking a large number of frames, a dedicated program will be much easier.

Feel free to PM me anytime I can be of assistance for Astrophoto stuff...

Nice set-up Eric,
I have used the Photoshop's Stack Mode for smart objects before when combining stack layers. It's a little slow but it works great. Thanks for the deepskystacker software link. Great info on that site as well.

Curiously, the Canon 5D Mark III and 1DX have a built-in multiple exposure mode (not actually developed for this purpose). This mode could potentially be used to stack a maximum of 9 raw exposures into 1 raw file in-camera. (With the option to only save this resulting raw file). It seems to average the stacks increasing S/N ratio similarly to what Photoshop Stack Mode does. I will do more tests on this.
Fred

Steve, Fred, et al thanks for the postings. Before reading this thread, I had made a personal commitment to stop spending for a while and quit enabling my photoholism ....well looks like another relapse is on its way

Fred Miranda wrote:
Nice set-up Eric,
I have used the Photoshop's Stack Mode for smart objects before when combining stack layers. It's a little slow but it works great. Thanks for the deepskystacker software link. Great info on that site as well.

Curiously, the Canon 5D Mark III and 1DX have a built-in multiple exposure mode (not actually developed for this purpose). This mode could potentially be used to stack a maximum of 9 raw exposures into 1 raw file in-camera. (With the option to only save this resulting raw file). It seems to average the stacks increasing S/N ratio similarly to what Photoshop Stack Mode does. I will do more tests on this.
Fred...Show more →

Cool idea Fred, I had not thought of that! The Nikon D800/E allows 10 frames on multiple exposure. I read the section in the manual, this will be great if it works. I can turn auto gain on or off. I think if I leave it off, the shots will eventually over expose. I just tested a series of 8 exposures at ISO 25,600 and the noise was nearly eliminated. Very cool. I just need to test it to see if the multiple exposures work well with 5 minute exposures or less. Thanks for mentioning the multiple exposures. I don't think I would have thought to try that.

Todd wrote:
Cool idea Fred, I had not thought of that! The Nikon D800/E allows 10 frames on multiple exposure. I read the section in the manual, this will be great if it works. I can turn auto gain on or off. I think if I leave it off, the shots will eventually over expose. I just tested a series of 8 exposures at ISO 25,600 and the noise was nearly eliminated. Very cool. I just need to test it to see if the multiple exposures work well with 5 minute exposures or less. Thanks for mentioning the multiple exposures. I don't think I would have thought to try that.

Todd,
I'm glad this is available in some Nikon SLRs as well. I have done some tests with 9 shots (max for the Canon 5D III) and noise is greatly reduced. From my calculation, with 9-10 shots, you get SNR increases by a factor of 3.
I really like the convenience of this being done quickly in-camera.
On top of that, you can turn LENR "On" and get dark frames added to your final RAW file at the same time "in-camera".
At the end you get a stacked / dark-framed processed single RAW file.

ISO1600 wrote:
i've been looking for a cheap tracking option, this skytracker sounds like a home run as far as what i've been in the market for.

I have the Astrotrac and ordered the iOptron Skytracker as well. (for being ultra portable)
I have tried the Vixen Polarie and it's a great product. Very precise and well built. The issues I had with it seem to be addressed with the new iOptron, like the battery life, scope illumination, and location of the scope.
There is also the price factor. The new iOptron comes with the scope for $399 and has a mini wedge for latitude adjustment built-in. So you don't need an extra gear head for it. As far as I know there is no Azimuth control so you will need to get a pan base like this one though.

With the Vixen Polarie, the scope goes in the same place where you attach your camera gear. So, after spending time aligning it, you need to be careful removing the scope and attaching your ball head and camera on the mount. Inevitably, this creates motion messing up your precise alignment. However, from my tests, it is ok for wide angle shots. Here are a couple wide angle shots taken with the Vixen Polarie (2-3 minute exposures)http://www.fredmiranda.com/forum/topic/1191586

You may ask. Why spend more for the Astrotrac? To me, they are different products. The Astrotrac is a mount that does it all. You can attach a telescope on it or if you are crazy like me, super-telephoto lenses.

You have the option of auto-guiding in one axis as well. With the Vixen Polarie or iOptron, there is a weight limitation (around 7 pounds now that Vixen updated this spec.) but you get ultra portability - Some folks had success attaching their 300 f/4 lenses on them. You have to consider balancing issues as well.

If your main interest is shooting nightscapes (blending your foreground/stars wide angle shots) you can't go wrong with any of them.

Fred Miranda wrote:
I have the Astrotrac and ordered the iOptron Skytracker as well. (for being ultra portable)
I have tried the Vixen Polarie and it's a great product. Very precise and well built. The issues I had with it seem to be addressed with the new iOptron, like the battery life, scope illumination, and location of the scope.
There is also the price factor. The new iOptron comes with the scope for $399 and has a mini wedge for latitude adjustment built-in. So you don't need an extra gear head for it. As far as I know there is no Azimuth control so you will need to get a pan base like this one though....Show more →

So for those of us going looking to purchase the iOptron Skytracker, the only additional piece of equipment we would need to purchase is the FEISOL panning base? I presume the iOptron is compatible with supporting RRS ballheads?

nburwell wrote:
So for those of us going looking to purchase the iOptron Skytracker, the only additional piece of equipment we would need to purchase is the FEISOL panning base? I presume the iOptron is compatible with supporting RRS ballheads?

-Nick

I ordered the Feisol for it because I want the unit to be ultra-portable. You can try using your RRS ball head, and dismiss the built-in wedge. (Set it to zero latitude).
From my experience in the freezing cold, a ball head is not the best tool for star alignment but if you have patience and time, it works. Steve seems to be happy using it on his Astrotrac and his wide-angle shots demonstrate that is works great. Another option is to get a gear head like the Manfrotto 410 but the Feisol panning base is only $39...